The IP Multimedia Subsystem (IMS) is an architectural framework for delivering Internet Protocol (IP) multimedia services. It was originally designed by the wireless standards body 3rd Generation Partnership Project (3GPP)...
To ease the integration with the Internet, IMS uses IETF protocols wherever possible, e.g. Session Initiation Protocol (SIP). According to the 3GPP, IMS is not intended to standardize applications but rather to aid the access of multimedia and voice applications from wireless and wireline terminals, i.e. create a form of fixed-mobile convergence (FMC)...
Alternative and overlapping technologies for access and provisioning of services across wired and wireless networks include combinations of Generic Access Network, soft switches and "naked" SIP. It is easier to sell services than to sell the virtues of "integrated services", but additionally the task to sell an IMS based on a single service is also difficult as there are often (cheaper) alternatives to creating and deploying that particular service. Since it is becoming increasingly easier to access content and contacts using mechanisms outside the control of traditional wireless/fixed operators, the interest of IMS is being challenged.
目前已经有很多基于互连网的增值业务，而且正在蓬勃发展，这些业务都不是电信运营商提供的。电信运营商仅仅是提供了一个通信的“管道”，却无法控制“管道”中的内容。而IMS本身就是期望通过自身的技术特性，将这些增值业务进行整合，使得运营商可以在这些原本不可控的增值业务中分一杯羹。 无奈的是，“同等质量，选择便宜的”是消费者的天性，因此第二段黑体字中才说“the interest of IMS is being challenged”（第二段黑体字的解释）
//运营商部署IMS，恰恰就是因为：运营商不想沦为“管道”提供商！信不信，淘宝之类的网站完全可以和提供IMS网络的运营商合作，共同赚取更多利润，只是现在国内的IMS网络尚处于试点阶段。
